Saw

ABSTRACT

A saw comprising a base plate 1 (FIG. 1), a disc 7 rotatably mounted on the base plate; clamping means disposed over the disc 7 and comprising forward elements 3, 3a and a backstop element composed of arms 18a, 18b (FIG. 2), and the arcuate member 19 joining the said arms, said clamping means being disposed over the disc 7, and a saw assembly 13, 14, 15, 16, 17 pivotally mounted on the machine via pin 11 (FIG. 1). The arcuate member 19 of the backstop is in bearing relation with the mount of the saw assembly adjacent the upper level of the arcuate member 19a, 19b. To accommodate different size workpieces, an auxiliary backstop 28 (FIG. 4) is provided to permit positioning a small workpiece in a more forward position with respect to the path of the saw blade, permitting more effective operation of the saw.

United States Patent Jagers [451 June 27, 1972 SAW [56] References CitedUNITED STATES PATENTS [72] Inventor: Leopold Jagers,Rudolf-Diesel-Str.-l, 535 1 81 569 H192 T tz 3 H 4 1 annewiEusklrcheD/Rhme and Germany 3,574,315 4/1971 Boultinghouse 143/6 H [22]Filed: Oct. 5, 1970 Primary Examiner-James M. Meister [21] App! 77825Attorney-Burgess,Dinklage&Sprung Related US. Application Data 1 ABSTRACT[63] Continuation-impart of Ser. No. 20,852, March 18, A Saw comprisinga base plate 1 (FIG' a disc 7 rotatably 1970 abandoned mounted on thebase plate; clamping means disposed over the disc 7 and comprisingforward elements 3, 3a and a backstop element composed of arms 18a, 18b(FIG. 2), and the arcuate [30] Foreign Application P i i D member 19joining the said arms, said clamping means being disposed over the disc7, and a saw assembly l3, l4, l5, 16, 17 Oct. 7, Germany 5 piyotanymounted on the machine via The ar. March 19, 1969 Germany ..P 19 13833.1 uate member 19 of the backstop is in bearing relation with themount of the saw assembly adjacent the upper level of the [52] U.S. Cl..83/ 169, 83/464, 83/467, arcuate member 19a, 19b. To accommodatedifferent size 83/490, 83/581, 143/6 H workpieces, an auxiliary backstop28 (FIG. 4) is provided to 51 Int. Cl. .3230 47 02, 823d 45 04 W111itPositioning a Small workpiece in a more forward p [58] Field of Search..83/l69, 464, 467, 468, 490, with respect to the p f h saw blade,permitting more effective operation of the saw.

15 Claims, 9 Drawing Figures I I I ll \91 *e il/ 11 III/I PATENTEDMUI972 SHEET 10F 7 lnrenlor: 1 0 76544,,

F'ATENTEBJum I972 3. 672 251 sum 20F 7 lnrenla'r:

P'A'TENTEDJum 1972 3.6?2251 SHEET 3 OF 7 lnrenfar:

P'ATE'N'TEDJM? 1872 3, 672 251 saw u or 7 FIG. 4.

ATTORNEYS PATENTEDJmmn 3.672251 sum 5 or 7 FIG. 5.

INVENTOR LEOPOLD JAGERS ATTORNEYS.

PKTENTEDJUH 27 I972 3. 672 2 51 SHEET 5 or 7 LEOPOLD JAGERS ATTORNEYS.

FIG. 7

INVENTOR LEOPOLD JAGERS BY ATTORNEYS.

SAW This application is a continuation-in-part of Ser. No. 20,852, filedMar. 18, 1970 and now abandoned BACKGROUND This invention relates to acold circular saw, i.e., a saw for cold-sawing metals. Cold circularsaws are conventional wherein the saw assembly comprising the sawingblade together with the driving motor thereof, is pivotabIe in thevertical saw blade plane relative to the work to be sawn, for instanceby means of a pivot pin which is mounted on a rotary disc, rotatableabout a vertical axis relative to the base plate. A backstop comprisinga vise and an abutment are disposed over the rotary disc, supportedthereon, and have a passage for the saw blade, and are secured to thebase plate for clamping the work.

In a conventional cold circular saw of this type, the abutment comprisestwo strips disposed in alignment, the saw blade being capable of passingthrough between said two strips, said strips being connected to oneanother at their sides facing away from the vise by means of asemi-circular arcuate member, said arcuate member engaging acomplementary circular groove of the rotary disc with a rib. In thisconventional saw, the rotary disc is loosely positioned in acomplementary recess of the base plate, on which it is moreoversupported through the intermediary of a flange. It cannot be avoided insuch an arrangement, in particular in cases of high saw loads, that theabutment is subjected to a slight vibratory movement relative to thebase plate as a result of the periodical loading of the saw teeth. It isof a decisive significance, however, for the useful life and for thewear of the saw blade that the work to be sawn is retained absolutelymotionless.

THE INVENTION An object of the invention is the provision of an improvedretaining means of the work to be sawn and of the abutment retaining thework to be sawn. This can be accomplished with cold circular saws of thetype referred to hereinbefore in that the upper margin of the abutmentengages the rotary disc at one point and the rotary disc is supported onthe base plate with a portion located outside of this point.

Preferably this arrangement is provided in such a way that the abutmentof the backstop comprises two strips positioned in alignment andpermitting the passage of the saw blades, said strips having aprojection at the side facing away from the vise which with its upperedge engages an accordingly upwardly extended projection of the rotarydisc, said projection of the rotary disc extending beyond the remainingperiphery of the rotary disc in radial direction and resting on the baseplate with its end. As a result of this arrangement, a rigid frictionalengagement is obtained between the part of the base plate carrying thevise, the work to be sawn, the abutment, the rotary disc, in particularthe elevated projection of the rotary disc, which serves as a mount forthe saw assembly, and that portion of the base plate, on which saidportion of the rotary disc rests, thus in particular the saidprojection. A particularly simple construction is obtained by simplyhaving the rotary disc closely resting on the base plate over its entirecircumference. This also insures that the rotatability of the rotarydisc cannot be impaired by sawing fines. Preferably, the rotary disc isdrawn down against the base plate by a suitable arrangement when it isto not be rotated. The rotary disc and the base plate have passages topermit coolants and fines to be discharged, said passages being arrangedin such a way that the discharge of the coolant is kept away from thesupporting location of the rotary disc on the base plate.

The invention also aims at achieving an improvement of such a circularsaw so that workpieces of a wide variety of widths (measurement fromforward to rear part of workpiece) can be held absolutely motionless sothat they can be cut with a minimum of stress on the saw. The minimumstress on the saw takes place when the substantially vertical plane inwhich the advance of the saw blade axis takes place in the case of asquare cutofi' (i.e., cut at right angle to length of workpiece) of theworkpiece runs through the center of the width of the workpiece (seeFIG. 6).

According to the invention, a circular saw of the abovenamed kind isconstructed in such a manner that the substantially vertical plane inwhich the sawblade axis is advanced in the case of a square cutofi ofthe workpiece is at a distance of several centimeters from theabove-mentioned backstop bars, and an auxiliary, removable backstop barattachment having two backstop arms whose faces are aligned with oneanother and having on its underside a groove parallel with thesesurfaces, the shape of the said groove matching the shape of thebackstop bars affixed to the base plate, can be mounted over thelast-mentioned backstop bars and set down virtually onto the surface ofthe turntable.

Preferably the auxiliary backstop bar attachment arms are rigidly joinedto one another by a connecting member which lies above the arcuateportion joining the backstop bars of the fixed backstop when theauxiliary backstop bar attachment is mounted on the principal backstopbars. Furthermore, a eutout to accommodate the sawblade is provided bothin principal backstop and in the auxiliary backstop bar attachment andflares away from the vise at a 45 angle to at least one side, and theauxiliary backstop bar attachment is displaceable longitudinally on thebackstop bars.

THE DRAWINGS With the foregoing object in view, together with suchadditional objects and advantages as may subsequently appear, theinvention resides in the parts, and in the construction, combination andarrangement of parts disclosed, by way of examples, in the followingspecification of certain modes of execution of the invention; referencebeing had to the accompanying drawings which form a part of saidspecification and in which drawings:

FIG. 1 is a side elevation view partly in section of a cold circular sawof this invention;

FIG. 2 is a front elevation partially in section of the saw taken alongline II-II of FIG. 3;

FIG. 3 is a top plan view, partially sectional view of the saw takenalong line III-III of FIG. 1;

FIG. 4 shows a top view of the circular saw according to the invention,in which the lever bearing the circular saw blade is cut away;

FIG. 5 shows the same arrangement as in FIG. 4, but with the auxiliarybackstop bar attachment removed;

FIG. 6 is a side elevation of the circular saw of FIG. 4;

FIG. 7 is a top view of FIG. 4, but with the saw making a 45 miter cut;

FIG. 8 is a top view of the auxiliary backstop bar attachment;

FIG. 9 is an end view of the auxiliary backstop bar attachment.

Referring to FIGS. l-3, a quadrangle base plate 1 has a groove 2 alongits front side for guiding a vise 3. In the middle thereof, it isprovided with a threaded bore 1b within an enlargement 1a, into whichbore a male threaded sleeve 4 is screwed in, the flange 4a of which isconnected to a hand lever 5. A circular-cylindrical projection 6 of acircular disc 7 is mounted in the sleeve 4, the margin 7a of which discis supported on a complementary circular surface 10 of the base plate 1.A ring 8 is inserted into the projection 6, which ring is abutted by theflange 4a of the sleeve 4. By pivotting the lever 5 about the axis ofthe sleeve 4, the abutment surfaces 7a are drawn down against theabutment surface 10; by pivotting the lever 5 in the opposite direction,the flange 4a is released from the ring 8 so that then the disc 7 merelyrests on the surface 1c as a result of its own gravity. In all cases,the surfaces 7a and 1c closely engage with one another, so that there nocoolant containing sawing fines can enter. The disc 7 can be rotatedabout its axis when tight engagement between the flange 4a and ring 8 isreleased by turning of lever 5 to loosen such engagement. This can bedone manually by having the operator of the machine grasp thetransmission 13 or the motor 14, which are pivotally mounted viaprojection or mount 10, on disc 7, to thereby pivot the disc 7 about itsaxis of rotation; for instance by 45, if a cut of 45 is intended; thesaw blade then is in the plane AA or C--C shown in FIG. 3. In FIG. 3those positions of the saw blade 15 and of the projection are indicatedin phantom. An arresting mechanism is provided for arresting the disc 7in the selected position, of which mechanism the handle 9 is illustratedin FIG. 1.

The rotary disc 7 is provided with a projection or mount 10 at onepoint, the end of which farthest away from the axis of rotation engagesa complementary annular surface of the base plate 1. A pin 11 ispositioned in the projection or mount 10, at the ends of which pin aforked projection 12 and a casing 13 are mounted, carrying the electricdriving motor 14 and furthermore supporting a transmission as well asthe bearing for the circular saw 15 and a protective hood 16 for thissaw and a manual lever 17 by means of which the casing 13 can bepivotted about the axis of the pin 1 1.

An abutment for the workpiece W has the form of two strips 18a, 18b(FIGS. 2 and 3) positioned in alignment and consisting of one piecetogether with a semi-circular arcuate portion or projection 19. Thestrips 180 and 18b are firmly connected to the plate 1 at their ends bymeans of bolts a, 20b. The projection 19 engages the rotary disc 7 attwo different points, namely in both cases at its outer margin; on theone hand, it engages a complementary surface 10b of the projection 10 ofthe rotary disc with its upper margin 19a; on the other hand it engageswith point 19b at its bottom side, which point rests on the planar topside of the rotary disc 7. A cavity 20 (FIG. 1) is provided underneaththe abutment points 19a-10b between the parts 19 and 10. The bearingsurfaces 19a-l0b are disposed adjacent the upper level of the arcuatemember 19. The spacing between the plane of the disc 7 on which theworkpiece is supported and the mid-elevation point of the bearingsurfaces l9a-10b can be about 2-5 cm, preferably 3-4 cm.

The vise 3 is capable of being clamped tight in the groove 2 of the baseplate in such a way that it is not capable of moving relative thereto.By means of its clamping jaws, the workpiece W can be clamped tightagainst the abutment 18a, 18b. A selfcontained force path is obtainedwhen tightening via the points at which the workpiece engages the jaws3a and the abutment 18a, 18b, as well as via the abutment points 19a,10b, and 100, 1d, said force path not being affected by the operation ofthe saw teeth.

The rotary disc 7 has a groove defined by walls 21 extending inclinedtoward the interior of the hollow cylindrical projection 6 of the rotarydisc in the vicinity of the saw blade 15, through which groove theliquid coolant can flow off together with sawing fines. Coolant whichmight flow off over the edge of the rotary disc 7 can be dischargedthrough ports 22 (FIG. 1) of the base plate 1, without it being able toimpair the bearing surfaces of the rotary disc 7 on the base plate. Anadjusting screw 23 provided on the casing 13, capable of engaging aneedle 24 (FIG. 1) of the projection 10 of the rotary disc, is providedfor limiting the pivot angle of the casing 13.

Referring to FIGS. 4-9, in a quadrangular base plate 1 there is mounteda turntable 7 which can be locked against rotation by a hand lever 5,the said turntable having a slot for the saw blade 15 and having aprojection or mount 10 to which, by means of a pin 11, there isarticulated a hand lever 17 which bears the sawblade 15 which is drivenby a motor 14 about the axis 25. By means of the hand lever 17,therefore, the saw blade 15 can be advanced in a substantially verticaldirection against the workpiece W. Two backstop bars 18a and 18b whichare in alignment with one another and fixedly joined together by ajoining piece 19 are fastened onto the base plate 1 by means of bolts20a and 20b such that their faces, which engage the workpiece W,substantially span the turntable 7. The upper marginal portion of 1190of part 19 has the shape of a cylindrical surface about the center axis26 of the turntable 7. The matching cylindrical surface of projection ormount 10 lies against this cylindrical surface. The substantiallyvertical plane in which the saw blade axis 25 is advanced during thesawing is at a distance of several centimeters, 5 cm, for example, fromthe contact plane of the backstop bars and 18b (see also FIG. 5). Acutout 19d is provided in the backstop bars 18a and 18b and theirjoining portion 19, so that miter cuts of as much as 45 can be made inaddition to square cuts.

An auxiliary backstop bar attachment 28, which is represented in FIG. 5and FIG. 6, is placed onto these backstop bars, which are especiallyeasy to see in FIG. 5, this being done as shown in FIGS. 4, 6 and 7.This auxiliary backstop bar attachment 28 has two backstop arms 28a and28b whose faces 28a and 28b are parallel to the faces 18a and 18b whenthe auxiliary backstop bar attachment is placed on the backstop bars.The auxiliary backstop bar attachment arms 28a and 28b are joined to oneanother by a flat joining portion 28d which, when attachment 28 ismounted in place, lies above the joining portion 19. The backstop arms28a and 28b have on their underside a groove 280 whose width is equal tothe width of the backstop bars 18a and 18b. The depth of groove 28ccorresponds to the height of the backstop bars 18a and 18b, so that thebackstop bar attachment 28, after it is mounted, extends all the waydown to turntable 7. The distance between the faces 28a and 28b and theadjacent parallel boundary surface of groove 280 can be half as great asthe distance between the surface in which the sawblade axis 25 moveswhen sawing and the backstop faces of the principal backstop bars 18aand 18b. The auxiliary backstop bar attachment 28 has a cutout 29corresponding to the cutout 19d in the joining portion 19 at backstop18a, 18b. Furthermore, the backstop bar attachment 28 has an elongatedhole 31 above the backstop bar 18a, through which a bolt 30 is passedwhich can be screwed into a threaded hole 32a.

The base plate has a groove 2 which is parallel to the faces of parts18b and 28a-28b and serves to carry a guiding member 36 of a vise 3. Inthe guiding member 36 a vise jaw 32 is advanceable at right angles tothe groove 2, so that the workpiece W can be held between the jaw 32 andthe backstop face 28a. On the outer end of the vise jaw 32 there ismounted a crosshead 37 bearing a second vise jaw 33 located on the otherside of the sawblade 15. This crosshead 37 has an elongated hole 34through which a bolt 35 screwed into vise jaw 32 passes, so that thecrosshead together with the vise jaw 33 lies close to the saw blade 15not only when the workpiece is being cutoff at a right angle (FIG. 4)but also in the case of a 45 miter cut (FIG. 7). As shown by FIGS. 4 and7, the workpiece is held between jaws 32 and 33 and backstop arms 28aand 28b in an excellent manner during every kind of cut.

The spacing of the plane of the axis of the saw blade and the engagingsurface of the principal backstop can be, as stated above, about 5 cm;as a range, can be mentioned 3-8 cm. The radius of the saw assembly fromthe pivot mounting thereof at pin 11 to the axis of the saw blade can beabout 15-40 cm, preferably l8-30 cm and the corresponding ranges for thecutting arc of the saw blade can be 20-35, preferably 25-30Notwithstanding the illustrated uses of the invention and the manners bywhich such use may be achieved, it is appreciated that changes andmodifications will suggest themselves to those skilled in the art bothfor uses similar to those illustrated as well as for other uses. Theinvention, therefore, is not to be deemed to be limited to the exactmode of execution above disclosed by way of example, and it will beunderstood that the invention embraces all such changes andmodifications in the parts, and in the construction, combination andarrangement of parts as shall come within the purview of the appendedclaims.

What is claimed is:

1. In a circular saw machine for cold-sawing metals compnsmg:

a. a base plate,

b. a disc for supporting the workpiece and rotatable mounted on the baseplate for rotation thereon,

c. laterally adjustable clamping means for engaging the forward portionof the workpiece,

. backstop clamping means for engaging the rearward side of theworkpiece including a clamping strip disposed on each side of thecutting plane joined together by a rearwardly extending semi-circulararcuate member, secured to the baseplate,

e. a saw assembly pivotally mounted on the machine comprising a sawblade and means for driving the saw blade, said mounting being forgenerally vertical advance of the saw blade relative to the disc forcutting of the workpiece,

the improvement which comprises:

f. the arcuate member of the backstop having a rearwardly disposed,bearing surface which is cylindrical with respect to the axis of thedisc disposed adjacent the upper level of the arcuate member,

g. said disc comprising a saw assembly mount disposed to the rear andoutwardly of said backstop arcuate member, for said pivot mounting ofthe saw assembly on the machine,

h. said saw assembly mount comprising bearing means for complementarybearing engagement with the bearing surface of the arcuate memberadjacent the plane of cutting of the saw blade.

2. Saw according to claim 1, said saw assembly mount comprisingsupporting means extending downwardly to supported engagement with thebase plate.

3. Saw according to claim 1, the disc being in engagement with the baseplate about the entire circumference of the disc.

4. Saw according to claim 3, and means for drawing the disc downwardlyinto tight fitting engagement with base plate.

5. Saw according to claim 1, said disc having means for discharge ofcuttings and coolant from beneath the saw blade.

6. Saw according to claim 5, said discharge means comprising adownwardly extending groove, the disc having an opening communicatingwith said groove for receiving cuttings and coolant therefrom.

7. Saw according to claim 1, wherein said base plate is outfitted withan opening disposed outwardly of the disc, for discharge of cuttings andcoolant.

8. Saw according to claim 1, the saw blade axis during the pivotingthereof for sawing, moving along a substantially vertical plane, saidplane being spaced several centimenters from the engaging surface of thebackstop clamping means, for sawing of a square cutoff, and an auxiliaryremovable backstop means for mounting on the first mentioned backstopmeans for selective spacing of the workpiece from said substantiallyvertical plane of the axis of the saw.

9. Saw according to claim 8, said spacing of the plane of the axis ofthe saw and the engaging surface of the first-mentioned backstop beingabout 3-8 centimeters, the radius of the saw assembly from the pivotmounting thereof to the axis of the saw being about 40-80 centimetersand the corresponding range for the cutting arc of the saw being 20-35.

10. Saw according to claim 8, said auxiliary backstop having twobackstop arms whose faces are aligned with one another and have on theirunderside a recess parallel to said faces whose shape is the same as theshape of the first mentioned backstop.

11. Saw according to claim 10, the arms of the auxiliary backstop beingjoined together by a joining member (28d) which, when the auxiliarybackstop bar attachment is mounted onto the first-mentioned backstop,lies above the arcuate of the first-mentioned backstop.

12. Saw according to claim 11, wherein a slot suitable to accommodatethe sawblade flares backward from the vise at an angle of about 45 to atleast one side, both in the first-mentioned backstop bars and theauxiliary backstop bar attachment.

13. Saw according to claim 8, wherein the auxiliary backstop isdisplaceable in its longitudinal direction on the first-mentionedbackstop bars (18a, 18B).

14. Saw according to claim 13, wherein means are provided for limitingsaid longitudinal displacement.

15. Saw according to claim 8, wherein the laterally adjusta ble clampingmeans (0) has on each side of the sawblade close to the plane of thesawblade in a square cutoff of the workpiece, a jaw which is advanceabletoward the first-mentioned backstop, and that one jaw is adjustable inrelation to the other jaw at right angles to the direction of advance ofthe jaws to such an extent that the two jaws grip the workpiece on bothsides of the sawblade even in the case of a 45miter cut.

1. In a circular saw machine for cold-sawing metals comprising: a. abase plate, b. a disc for supporting the workpiece and rotatable mountedon the base plate for rotation thereon, c. laterally adjustable clampingmeans for engaging the forward portion of the workpiece, d. backstopclamping means for engaging the rearward side of the workpiece includinga clamping strip disposed on each side of the cutting plane joinedtogether by a rearwardly extending semi-circular arcuate member, securedto the baseplate, e. a saw assembly pivotally mounted on the machinecomprising a saw blade and means for driving the saw blade, saidmounting being for generally vertical advance of the saw blade relativeto the disc for cutting of the workpiece, the improvement whichcomprises: f. the arcuate member of the backstop having a rearwardlydisposed, bearing surface which is cylindrical with respect to the axisof the disc disposed adjacent the upper level of the arcuate member, g.said disc comprising a saw assembly mount disposed to the rear andoutwardly of said backstop arcuate member, for said pivot mounting ofthe saw assembly on the machine, h. said saw assembly mount comprisingbearing means for complementary bearing engagement with the bearingsurface of the arcuate member adjacent the plane of cutting of the sawblade.
 2. Saw according to claim 1, said saw assembly mount comprisingsupporting means extendinG downwardly to supported engagement with thebase plate.
 3. Saw according to claim 1, the disc being in engagementwith the base plate about the entire circumference of the disc.
 4. Sawaccording to claim 3, and means for drawing the disc downwardly intotight fitting engagement with base plate.
 5. Saw according to claim 1,said disc having means for discharge of cuttings and coolant frombeneath the saw blade.
 6. Saw according to claim 5, said discharge meanscomprising a downwardly extending groove, the disc having an openingcommunicating with said groove for receiving cuttings and coolanttherefrom.
 7. Saw according to claim 1, wherein said base plate isoutfitted with an opening disposed outwardly of the disc, for dischargeof cuttings and coolant.
 8. Saw according to claim 1, the saw blade axisduring the pivoting thereof for sawing, moving along a substantiallyvertical plane, said plane being spaced several centimenters from theengaging surface of the backstop clamping means, for sawing of a squarecutoff, and an auxiliary removable backstop means for mounting on thefirst mentioned backstop means for selective spacing of the workpiecefrom said substantially vertical plane of the axis of the saw.
 9. Sawaccording to claim 8, said spacing of the plane of the axis of the sawand the engaging surface of the first-mentioned backstop being about 3-8 centimeters, the radius of the saw assembly from the pivot mountingthereof to the axis of the saw being about 40- 80 centimeters and thecorresponding range for the cutting arc of the saw being 20*-35*. 10.Saw according to claim 8, said auxiliary backstop having two backstoparms whose faces are aligned with one another and have on theirunderside a recess parallel to said faces whose shape is the same as theshape of the first mentioned backstop.
 11. Saw according to claim 10,the arms of the auxiliary backstop being joined together by a joiningmember (28d) which, when the auxiliary backstop bar attachment ismounted onto the first-mentioned backstop, lies above the arcuate of thefirst-mentioned backstop.
 12. Saw according to claim 11, wherein a slotsuitable to accommodate the sawblade flares backward from the vise at anangle of about 45* to at least one side, both in the first-mentionedbackstop bars and the auxiliary backstop bar attachment.
 13. Sawaccording to claim 8, wherein the auxiliary backstop is displaceable inits longitudinal direction on the first-mentioned backstop bars (18a,18B).
 14. Saw according to claim 13, wherein means are provided forlimiting said longitudinal displacement.
 15. Saw according to claim 8,wherein the laterally adjustable clamping means (c) has on each side ofthe sawblade close to the plane of the sawblade in a square cutoff ofthe workpiece, a jaw which is advanceable toward the first-mentionedbackstop, and that one jaw is adjustable in relation to the other jaw atright angles to the direction of advance of the jaws to such an extentthat the two jaws grip the workpiece on both sides of the sawblade evenin the case of a 45*miter cut.